• State Resolved
  • Locked Locked
  • Replies 5 replies
  • Subscribers 30 subscribers
  • Views 462 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

ESD protection of LDC1000 inductance

Gerardo Vanoni
Prodigy 220 points

Hello,

since the (PCB-) inductor of the analog front side will be close to ESD-generating sources, I want to improve the ESD tolerance of the circuit. The HBM of 1kV / CDM 250V is too low for my application.

Would it be feasible / adviced to use a bidirectional ultra low capacitance ESD protection diode, e.g. PESD18VF1BL (http://www.nxp.com/documents/data_sheet/PESD18VF1BL.pdf), in parallel with the inductor? What do you think?

Alternatives or other ideas?

Thanks & regards

Gerardo

  • 0
    TI__Intellectual 2790 points

    Hi Gerardo,

    There is an internal 5V clamp and an absolute maximum of 8mA on INA/INB.  It is possible to put external clamps on each pin to common.  To avoid damaging the internal clamp, we recommend lower voltage clamps/TVS at 4V.  Keep in mind that these will have to be fast to avoid affecting the frequency count.

    Thanks,

  • 0 in reply to Charles Cheung*
    Prodigy 220 points

    Hi Charles,

    what is the internal negative clamp on INA/INB? Are the 4VPP (Asensor_MAX) centered to +2.5V or to GND?
    In other words: bidirectional TVS or unidirectional + LowCap-Shottky (i.e. 1PS10SB82, http://www.nxp.com/products/rf/diodes/schottky_diodes_low_capacitance_rf/1PS10SB82.html)? What devices / combination of devices would you recommend?

    Shouldn't the TVS better have a Vrwm of 5V, in order to avoid clamping of the normal swinging?

    On the other hand, the inputs are (as of datasheet) theirselves ESD protected up to 1kV (HBM) / 250V (CDM), so the external TVS should only "help" to kill higher energies. Or am I misunderstanding a spec?

    Thanks & regards
    Gerardo

  • 0 in reply to Gerardo Vanoni
    TI__Intellectual 2790 points

    Negative clamp is 0.6V to GND.  4VPP centered to GND, so differential is 8V.

    I would recommend unidirectional TVS on each of the two INA/INB pins to GND.

    Again, that is not an issue since these devices are wired to common.

    Yes, for higher energies.

    Thanks,

  • 0 in reply to Charles Cheung*
    Prodigy 220 points

    Hello,

    what do you mean by "that is not an issue since these devices are wired to common"?

    Regards

    Gerardo

  • 0 in reply to Gerardo Vanoni
    TI__Intellectual 2790 points

    That is a response to having the TVS rev. standoff be 5V, since the devices proposed are not bi-directional.  Having each device at 4V VRWM will be effectively 8V differential.  (the clamps mentioned in the initial post are positive uni-directional to GND)

    Thanks,